Small changes in form or movement, such as changes in the angle of a hand or the movement of a head can significantly reduce the swimmer's speed and increase fatigue. Heretofore, only lap counters and timing devices such as stop watches have been used for evaluating a swimmer's performance. The effects of small changes in form and movement have either been overlooked or not been readily detectable by either the swimmer or an observer such as a coach. Consequently, there was no way for the swimmer to know, while swimming, whether a specific change in his swimming technique increased or decreased his speed.
Linden, U.S. Pat. No. 4,796,987; Kreutzfeld, U.S. Pat. No. 4,823,367; and Malone, U.S. Pat. No. 4,780,085 are exemplary of the prior art. Linden merely discloses a stop watch mounted in a transparent lens of a goggle, mask, or shield worn by a swimmer. The stop watch reset button is manually activated by the swimmer before the swimmer starts swimming and after the swimmer stops swimming.
Kreutzfeld discloses an apparatus for counting the number of laps of a swimmer comprised of a portable unit worn by the swimmer and a stationary unit which establishes a zone of detection. Each time the portable unit passes the stationary unit a signal is conveyed to register a completion of a lap.
Malone discloses a lap timing device consisting of a clock/timer, a switch for starting the clock/timer and a proximity sensor for detecting a completion of a lap.